Some cyanobacteria can produce nerve, liver or derma toxins (“cyanotoxins”), making them dangerous to humans and animals. Because they occur in water that humans and animals either drink or come into contact with, it is necessary to test for their occurrence.
A problem with testing for cyanotoxins is that they occur not only in the water, but also inside cyanobacterial cells present in the water. Therefore, testing usually includes an initial step (freeze and thaw, boiling, microwaving, freeze-drying) that allows the toxins to be liberated from the bacteria into an aqueous medium, accessible to testing. This aspect of toxin testing has room for improvement, however, because faster means for efficient cyanobacterial extraction are needed. Although such improvement would be generally advantageous, it is of particular importance when the assays are done “in the field”, rather than at a laboratory some distance from their source, and a rapid answer is necessary.
Cyanobacteria are a large and varied phylum of aquatic bacteria. They are also known as “blue-green algae”, but are not related to any other algae, which are all eukaryotes. They occur in man-made reservoirs and naturally-occurring water sources, such as lakes, hot springs, rivers, marshes, streams, ponds and salt waters, as well as ocean and sea coastal areas. Depending on the species and environmental conditions, cyanobacteria may organize into large masses, referred to as “blooms”, in which the bacteria may be filamentous, in sheets or even hollow balls.
There are numerous cyanobacterial species. A single cyanobacterial species can occur as either a toxic or nontoxic population, depending on environmental conditions or stress. Blooms that test non-toxic one day can turn toxic the next day.
One of the present inventions comprises the use of an appropriate metal salt, as specified herein, as a releasing agent to liberate cyanotoxins and other molecules rapidly from cyanobacteria. In a related invention, liberation of the cyanotoxins is achieved by exposing the cyanobacteria to such a metal salt and subsequently to ammonium chloride.